DOI 10.2478/pesd-2018-0012 PESD, VOL. 12, no. 1, 2018
ESTIMATION OF ENVIRONMENTAL QUALITY BASED ON
ECOMETRIC CLIMATIC INDICATORS (ON THE EXAMPLE OF
THE REPUBLIC OF MOLDOVA)
Duca Gh 1, Nedealcov Maria 2, Ivanov Violeta2
Key words: Ecometric climatic indicators, environmental quality, dry and
droughty periods, potential evapotranspiration
Abstract. Aridity in new climatic conditions requires indexes which could
adequately explain this process. All the more so, the quantities of atmospheric
precipitations also continue to increase on the background of the temperatures
increase in the conditions of the Republic of Moldova. Their variable
character in the last period of time with the installation of dry and droughty
periods alternating with rainy flood-provoking periods determines the
selection of the most optimal ecometric indexes that could correctly explain
the occurrence of pronounced desertification in the last period of time.
Introduction
Climatic ecometric indexes (Stanciu, 2005), serve as indicators in estimating
environment’s quality using climatic parameters such as temperature and amount
of atmospheric precipitation in the annual, seasonal or monthly aspect, air
humidity, actual and potential evapotranspiration - climatic indexes considered to
have a direct projection in estimating the degree of desertification of a territory.
Thus, climatic ecometric indexes can express the deficit and the excess of
humidity, and thus, the degree of desertification on the basis of the temperatures
increase. We should note that the initial data was collected from the meteorological
stations of the State Hydrometeorological Service.
1Moldova’s Academy of Sciences 2Institute of Ecology and Geography, Republic of Moldova
Duca Gh , Nedealcov Maria, Ivanov Violeta
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1. Initial materials and research methods
Thus the Republic of Moldova has a meteorological network that currently
includes 17 meteorological stations. The latter has been doing observations over
several decades. The study period ranged from 1961 to 2016, being mentioned as a
contemporary period in previous research (Nedealcov, 2012), The collected
database was stored in the EXCEL format, which was then used in the
STATGRAPHICS CENTURION XVI software to perform various statistical
calculations (fig. 1).
Fig.1. Statistical software Statgraphics Centurion XVI in statistical data processing
The data collected in the Surface Water Quality Guidelines elaborated by the
State Hydrometeorological Service Anuar, 2015), according to the Water Pollution
Index (IPA), had served as information support in the assessment of surface water
quality. It should be noted that IPA is classified by 7 classes and is calculated by a
fixed number of parameters (6) : ammonium nitrogen, nitrate nitrogen, petroleum
products, phenols, dissolved oxygen and biochemical oxygen demand at 5 days.
To illustrate the sequence of rainy and arid months, the Lang Index (Ivanov,
2017) is used in the literature, which takes into account the precipitation-
temperature ratio, serving as an indicator of the water inlet and outlet of the system,
and the temperature serving as one of the main evapotranspiration factors:
(1)
The data in Table 1 reflects the numerical correlation between the Lang index
and the characteristic climate of the area for which the assessment is made.
Estimation of environmental quality based on ecometric climatic indicators
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Table 1. The numerical correlation of the Lang index with the characteristic climate
R Climate type
>160 Humid
160-100 Temperately humid
100-60 Temperately warm
60-40 Semiarid
40-20 Steppe
0-20 Desert
The definition of climatic types according to the Dantin-Revenga coefficient
(Stanciu, 2005), could complete the highlighting of the real degree of
desertification on the territory of the Republic of Moldova in the context of climate
changes (tab. 2). The Dantin-Revenga thermo-pluviometric index (DR) was used
more in the literature from abroad, and has the following aspect:
(2)
where:
T - is the average annual temperature
P - The amount of annual rainfall
Table 2. Climate types definition according to Dantin-Revenga Coefficient (DR)
DR Climate
0-2 Humid
2-3 Semiarid
3-6 Arid
>6 Extremely arid (desert)
The edifying degree of continentality may also be the Diekman Index
(Stoenescu, 1951). It is expressed by the difference between the sum of the
precipitation quantities in the interval May-July and August-September interval
(fig. 2).
In the temperate-oceanic climate with high autumn rainfall, the values of the
difference are negative, in Central Europe the values approach 0, and in the
continental climate, with abundant rainfalls at the end of spring and early summer,
the values of the difference are positive, even exceeding the values of 100 mm
(Stoenescu, 1951). For pluviometric stations with observation datasets longer than
40 years, in the Sub Carpathians of Moldova, the Diekman Indexes’ (Id) difference
values are all positive at values above 100 mm, highlighting a continental
Duca Gh , Nedealcov Maria, Ivanov Violeta
152
precipitation regime. The highest values of the Diekman Index are recorded in
sheltered areas with eastern exposure to the Carpathians, where convective
processes are intense in the early summer (Stoenescu, 1951).
Fig. 2. Calculation of the Diekman Index (1981-2016)
The estimation of the uninterrupted duration with pluviometric deficiency
during the year was performed based on the Gaussen ombrotermic diagram
(Stanciu, 2005), which allows the graphical demonstration of the relationship
between temperature and precipitation. The construction of the diagram is based on
a double scalar rectangular system consisting of a horizontal axis and two vertical
axes. The modality of construction included: drawing on the horizontal axis of the
months of the year; on the left vertical axis - the average monthly temperature (5
°C); and on the left vertical axis - the monthly average values of rainfall, which is
double when compared with the temperature (10 mm), were placed. It is important
to mention that depending on the location of the two curves with respect to each
other (the thermal curve is the red one and the ombric one - blue), the humidity
deficiency interval is determined, i.e. if the thermal curve exceeds the ombric. In
most cases, this coincides with the summer period.
One of the basic indexes reflecting the degree of aridity of a territory is the
Aridity Index (Ia) proposed by UNEP (1992) and UNESCO (1979) being
expressed as the ratio between the amount of atmospheric precipitation and
evaporability (Păltineanu et al, 2007).
Estimation of environmental quality based on ecometric climatic indicators
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0E
PIa (3)
Depending on the regional variation of its values, four categories of aridity for
territories were established on global level (UNEP, 1992).
Table 3. UNESCO / UNEP classification of land according to degree of aridity
Category Aridity index Global area (%)
Hyperarid < 0.05 7.5
Arid 0.05 -0.20 12.1
Semi-arid 0.20 -0.50 17.7
Dry subhumid 0.50 -0.65 9.9
Therefore, the UNESCO/UNEP aridity index shows the existence or absence
of humidity deficiency in the analyzed area (tab.3). The limit between the semi-arid
climate and the dry subhumid one is 0.50 units - a limitation in the characterization
and conditions of aridity on the territory of the Republic of Moldova.
2. Analysis of the obtainde results
Therefore, traditionally, the estimation of the degree of moisture assurance is
performed on the basis of the Seleaninov hydrothermal coefficient (CHT)
(Nedealcov, 2012).
Climate change in recent years, as shown by previous research, has a
substantial influence on its values, as demonstrated by the digital map of its
distribution in space with the inclusion of numerical values in recent years (fig. 3).
So, the estimation of the degree of aridity by means of the hydrothermal
coefficient Seleaninov does not adequately reflect the state of the present climate
on the territory of the Republic of Moldova.
To obtain comparative estimates to previous research (Nedealcov, 2012), the
Aridity Index (Ia) was calculated for the vegetation period taking into account the
entire updated period (1961-2016).
We were able to conclude that it reaches the limit of 0, 20 units that
characterize the climate as arid in the temporal aspect in the south of the country in
certain specific years (fig. 4), and especially in the last decades. These values are
substantially different from the values that characterize the north of the country,
where it varies within limits exceeding the climate characterized as dry-subhumid
(0.65).
Duca Gh , Nedealcov Maria, Ivanov Violeta
154
Fig. 3. Spatial distribution of Seleaninov hydrothermal coefficient (1960-2016)
Fig. 4. Time analysis of the Aridity Index (Ia) for the Republic of Moldova territory
The cartographic modeling of Ia reveals the fact that the climatic conditions
are characterized by the limit (0.5) between the semi-arid and dry climate during
the vegetation period according to the values at Balti Steppe (to the north), in the
south, southeast and the central-eastern part of the country (fig. 5). Values above
0.68 are characteristic for altitudinal territories in the northern and central parts of
Bravicea
Briceni
Baltata
Chisinau
Cornesti
Cahul
Comrat
Camenca
Dubasari
Falesti
Leova
Soroca
Tiraspol
Stefan Voda
0.86
0.9
0.94
0.98
1.02
1.06
1.1
1.14
1.18
1.22
1.26
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1.34
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Briceni
Chișinău
Cahul
Estimation of environmental quality based on ecometric climatic indicators
155
the country. We also should mention that values are lower than those obtained in
previous research, which serves as evidence that climatic conditions became more
arid during the growing season.
Fig. 5. The spatial distribution of aridity Index (Ia) (1960-2016)
Therefore, the increase in thermal maximums, the installation of dry periods in
the last period of time, the tendency to intensify the evaporization process, the
numerical increase of the values that characterize the climatic water deficit
condition the estimation of the complex indexes by which the degree of
continentality of a regional climate can be made evident. According to (Stoenescu,
1951; Anuar 2015), the Diekman Index (Id) can be considered as an edifier of
continentality according to the atmospheric precipitation regime. It is expressed by
the difference between the sum of the precipitation quantities in the May-July and
August-September interval (fig. 6.a). In Fig. 6.b. modified Id data is presented
taking into calculation October for the second interval as in recent years there is an
essential change in the atmospheric precipitation regime. Regardless of the fact that
in the second case the Id values are diminished for the last years, we consider it
useful to introduce the October in calculation in order to highlight the actual
manifestation of the pluviometric regime in the context of the regional climate
warming. a
Bravicea
Briceni
Baltata
Chisinau
Cornesti
Cahul
Comrat
Camenca
Dubasari
Falesti
Leova
Soroca
Tiraspol
Stefan Voda
Balti
0.44
0.5
0.56
0.62
0.68
0.74
0.8
0.86
0.92
semiarid
uscat semiumed
Duca Gh , Nedealcov Maria, Ivanov Violeta
156
b
Fig. 6. Multiyear dynamics of Diekman Index, m. Chisinau (1891-2016)
Thus, the analysis of the multiannual dynamics of the Diekman Index over a
period of more than a century demonstrates that in most years it has positive
values and expresses the degree of continentality of regional climate. The period
with the significant values of Id when these exceed the limit of 100 mm belongs to
the end of the 40s and to the beginning of the 90s of the last century when the
precipitation in May, June, July prevailed over the pluviometric quantities
observed in August, September and October (fig. 6 a, b).
Absolute maximum values date back to 1948, when they were 533 mm (tab.
4), the multiannual average being 59.7 mm. The calculation of the intensity and
frequency of the Diekman Index reveals (tab. 4) that the variability limits were
between 45.7 and 140.9 mm during the series of instrumental observations in 54
cases and in 14 cases they were characterized by values of 140.9 ... 236.2 mm, fact
confirmed by the analysis of the graph of the quintile proportion of the indexes
(fig. 7).
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Estimation of environmental quality based on ecometric climatic indicators
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Table. 4. Id’s intensity and frequency, m. Chisinau (1891-2016)
Class Lower limit Upper limit Frequency Relative frequency
1 -240,0 -192,381 2 0,0168
2 -192,381 -144,762 1 0,0084
3 -144,762 -97,1429 2 0,0168
4 -97,1429 -49,5238 8 0,0672
5 -49,5238 -1,90476 13 0,1092
6 -1,90476 45,7143 23 0,1933
7 45,7143 93,3333 31 0,2605
8 93,3333 140,952 23 0,1933
9 140,952 188,571 8 0,0672
10 188,571 236,19 6 0,0504
11 236,19 283,81 1 0,0084
12 283,81 331,429 0 0,0000
13 331,429 379,048 0 0,0000
14 379,048 426,667 0 0,0000
15 426,667 474,286 0 0,0000
16 474,286 521,905 0 0,0000
17 521,905 569,524 1 0,0084
Fig. 7. Quantities of the Diekman Index calculated for the period of instrumental
observations (1891-2016)
Aridity in new climatic conditions requires indexes which could adequately
explain this process. All the more so, the quantities of atmospheric precipitations
also continue to increase on the background of the temperatures increase in the
Indicele Diekman, st.Chisinau (1891-2016)
pro
po
rtia
Quantile
-200 0 200 400 600
0
0,2
0,4
0,6
0,8
1
Duca Gh , Nedealcov Maria, Ivanov Violeta
158
conditions of the Republic of Moldova. Their variable character in the last period
of time with the installation of dry and droughty periods alternating with rainy
flood-provoking periods determines the selection of the most optimal ecometric
indexes that could correctly explain the occurrence of pronounced desertification in
the last period of time.
The spatial estimation of the maximum values of the Diekman Index recorded
in 1948 (fig. 8) indicates that the most vulnerable territory for the increase of
continentality was the territory located in the western central part, where the most
essential pluviometric values prevailed for May, June July compared with August,
September, October.
Fig. 8. The maximum values of the Diekman Index on the territory of
the Republic of Moldova, 1948
In conclusion we find that the precariousness of the fall of the atmospheric
precipitation in the second half of the warm season and the decrease of the rainfall
in May, June and July fall within the limits of the corridor with values from 0 to
100 mm. At the same time, in the certain years that have been characterized as dry
such as 2007, 2012 the degree of aridity has extremely dangerous influence on the
quality of surface waters. These relate to the development of a registry with
Briceni
Chisinau
Cornesti
Cahul
Comrat
Dubasari
Leova
Soroca
Tiraspol
160
190
220
250
280
310
340
370
400
430
460
490
520
Estimation of environmental quality based on ecometric climatic indicators
159
several indexes that characterize the degree of climate continentality in order to
highlight the desertification process in the context of climate change.
In our opinion, one of these indexes is the Lang (IL) ecometric index that can
illustrate both the rainy and arid months sequence. It takes into account the
precipitation - temperature ratio, as an expression of water inlet and outlet of the
system, temperature being one of the main factors of evapotranspiration. The
results obtained are extremely useful in the current estimation of regional surface
water resources.
The calculation of the statistical indexes revealing the multiannual average for
the last period of time (1961-2016) shows that according to Il, the north of the
country is characterized by warm temperate climate (76.2) and in the central and
southern part according to the values of this index (55.4 ... 53.3), the climate is
characterized as semiarid. The most insignificant values of the Lang Index (IL) in
the north of the country constituted 36.1, in the central part - 31.9 and in the south
the lowest values were 29.8. At the same time, the highest values of IL were
registered in the northern republic, representing 121.5. The essential variability of
this index is also expressed by the sigma values (tab. 5).
Table 5. Statistical indexes that characterize the Lang Index (IL)
Statistical
indexes
Briceni Chișinău Cahul
IL
annual
IL
summer
IL
July
IL
annual
IL
summer
IL
July
IL
annual
IL
summer
IL
July
X 76,2 12,9 4,9 55,4 8,9 3,1 53,3 9,0 2,9
σ 20,7 4,2 3,3 12,7 3,2 1,8 13,5 4,0 2,1
Minimum 36,1 2,9 0,2 31,9 2,7 0,2 29,8 2,6 0,0
Maximum 121,5 23,3 16,3 85,8 17,6 7,6 53,3 9,0 2,9
Therefore, the great climatic variability of the Lang Index determines the
specificity of its manifestation in the new climatic conditions. The analysis of its
annual manifestation shows that in 41 cases in 55 years, in the north, the climate
has been characterized as a warm temperate climate. As we move towards the
central regions, only in 20 cases the climate was characterized as warm, in 28 cases
it was established as a semiarid.
Duca Gh , Nedealcov Maria, Ivanov Violeta
160
a
b
c
Fig. 9. Dynamics of the Lang (IL) ecometric index, in annual (a),
seasonal (b), monthly (c) aspects
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Estimation of environmental quality based on ecometric climatic indicators
161
The number of cases with a steppe climate increases from 1 to 7. The years
with warm temperate climate continue to decrease and the years with steppe
climatic up to 25 continue to increase in the south of the country. It increases
significantly, i.e. up to 13 cases, when the climate was characterized as steppe (fig.
9). a
b
c
Fig. 10. The regional trends of the Ecometric Lang Index (IL), a-Briceni, b-Chisinau, c-
Cahul
Duca Gh , Nedealcov Maria, Ivanov Violeta
162
According to its analysis at smaller scales, namely in the seasonal and
monthly aspect (Fig. 9 b, c), we note that the climate is characterized as desert
throughout the country.
The trend with which this phenomenon manifests (fig. 9 a, b, c) demonstrates
that the desertification process will continue throughout the country in the future.
At the same time, we find that in the north of the country (fig.10 a) this trend is
much more pronounced, which is necessary to be taken into account in the
monitoring of surface waters limited in the conditions of the current climate.
Thus, under the conditions of climate change, we observe a decreasing
tendency for values and therefore the process of desertification intensifies on the
territory of the Republic of Moldova (fig.10 a, b, c), especially in the summer
season.
The analysis of the low values of the Lang Index (Table 6) shows that of the
top 10 years with the most significant values 5 years in the northern part of the
country, 6 years in the center and 7 years in the south of the country belong to the
last two decades (2000-2015), which allows us to conclude that the process of
desertification is intensifying recent time.
Table 6. Years with the lowest values of the Lang Index (1961-2016)
Briceni Chișinău Cahul
Anii IL Anii IL Anii IL
2015 36,1 1990 31,9 2003 29,8
2009 45,9 2015 35,8 2000 30,5
2000 46,5 1994 36,7 1990 31,6
2011 47,8 2000 39 1994 33,9
1994 48 1982 39,2 2006 33,9
1983 48,2 2009 39,2 2009 34
1990 49,7 2007 39,8 2011 35
1982 52,3 2008 41,2 1992 36,2
1961 54,5 2011 41,2 2008 37,3
2004 57,2 1992 41,3 2015 38,5
The estimation of the uninterrupted rainfall duration during the year based on
the Gaussen ombrothermic diagram shows that it varied significantly from north to
south in some years.
Thus, for example, in 2015 the pluviometric deficiency in the north of the
country was installed between May and September, in the center - in April and in
the south of the country the longest duration with a pluviometric deficit was
Estimation of environmental quality based on ecometric climatic indicators
163
a
b
c
Fig. 11. Gaussen’s ombrothermic diagram (a- Briceni, b-Chisinau, c-Cahul)
registered from March to October (fig.11a, b, and c). Undoubtedly, these
evaluations are extremely useful in the realistic estimation of aridity conditions in
-5,0
0,0
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Duca Gh , Nedealcov Maria, Ivanov Violeta
164
the context of climate change, especially in countries with unstable humidity
regimes of which the Republic of Moldova is a part.
The obtained results lead to the conclusion that in some extreme years the
uninterrupted dry periods can essentially vary in the territory and hence influence
the quality of the surface waters differently. We consider it useful to apply a series
of climatic ecometric indexes that could scientifically argue the manifestation of
this process in order to concretize the specificity of aridity in the new climatic
conditions.
Together with some ecometric indexes described above, the Dantin-Revenga
coefficient was also taken into account. It emphasizes on climate continentality and
reveals that in present, 20 -22 cases of semi-arid climate were established,
especially in the central and southern part of the country (fig. 12), in the south of
the country the climate was characterized as arid during five years.
Fig. 12. Evolution the Dantin-Revenga coefficient (1961-2016)
Thus, the climate was established as semiarid in 6 cases (1983, 1994, 2000,
2009, 2011, and 2015) in the north of the country, in Briceni. Arid conditions,
according to the Dantin-Revenga Coefficient, were not recorded for the study
period (1961-2016) in this area of the country. 20 years (1961, 1967, 1973, 1975,
1982, 1986, 1989, 1990, 1992, 1994, 1999, 2000, 2003, 2007, 2008, 2009, 2011,
2013, and 2015) with semiarid climatic conditions, and 1990 was classified as arid
in the central part of the country, in Chisinau. Semiarid climatic conditions were
established during most of the years (1967, 1973, 1977, 1982, 1986, 1989, 1990,
1992, 1994, 1995, 2000, 2003, 2004, 2005, 2006, 2007, and the southern climate
was recorded as arid during 5 years (1990, 1994, 2000, 2003, 2006) (fig.12).
0
0,5
1
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2
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3
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4
1961
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Briceni
Chisinau
Cahul
semiarid
arid
Estimation of environmental quality based on ecometric climatic indicators
165
a
b
c
Fig. 13. The values of dissolved oxygen (a), ammonium ion pollution (b),
and oxygen’s biochemical consumption (c) in 5 days (CBO5)
According to the data of the physico-chemical investigations carried out by
the State Hydrometeorological Service during the year 2015, the quality of the
Dniester River corresponds to the third class (moderately polluted) in all the
0
0,05
0,1
0,15
0,2
0,25
0,3
0,35
2010 2011 2012 2013 2014
0
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40
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140
2010 2011 2012 2013 2014
0
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2010 2011 2012 2013 2014
Duca Gh , Nedealcov Maria, Ivanov Violeta
166
monitored sections, except for the south-east of the country (Palanca village),
where the water quality is attributed to the fourth (polluted) class, due to the low
dissolved oxygen concentrations, largely determined by the establishment of the
uninterrupted droughts that year. The monitoring of the water quality in Prut on the
territory of the Republic of Moldova, performed monthly in 8 sections reveals the
fact that for most of the sections monitored on the Prut River was certified as the
second quality class except for the village of Lipcani, which was assigned quality
class I. So, in the northern part of the Prut basin, the highest quality class is
attributed to oxygen. During the last 5 years, the quality of Prut water, according to
the IPA, is characterized by a level of pollution with non-essential deviations. The
IPA ranged from 0.62 (Class II - Clean) in Ungheni t. section, 2010, up to 1.34
(class III - moderately polluted) in Valea Mare v. section in 2013. Regarding the
quality of water in Danube River during the last 5 years, in the monitoring section
of the DMCM – Giurgiulesti v., a slight increasing trend is observed in the level of
pollution in the dry years in the region (2011, 2012, 2014) (according to IPA) due
to the increased evaporability within this area.
So, in certain years, the quality of the Dniester, Prut, Danube Rivers (fig.13 a,
b, c) can undergo essential changes, characterized by moderate pollution due to
biogenic elements, copper compounds, phenols, petroleum products.
The quality of water in small rivers can be characterized by a high degree of
pollution with ammonium ions, nitrite, copper compounds, with a high level of
biochemical oxygen demand (CBO5) and a low level of oxygen dissolved in water
- determined to a great extent also by the increase of the desertification, especially
in the south of the country, where this influence is felt more significantly (fig. 13).
Therefore, highlighting the regional particularities of desertification in the new
climate conditions requires the indexes which could adequately explain this
process. The results obtained are extremely useful in the proper management of
surface water resources. It has been found that, the level of eutrophication increases
in extremely dry years, and the degree of water pollution may double due to the
concentration of pollutants as a result of increased evaporability.
Conclusions
In conclusion we would like to state that the uneven distribution of water
resources and climatic changes, which has become more and more obvious in
recent years, can lead, according to the estimates, to the occurrence of arid areas in
the south and south-east of the country.
The results of the research on the impact of climate change on water resources
imply the long-term development of new criteria and techniques for estimating the
degree of desertification, including the involvement in research of a huge amount
Estimation of environmental quality based on ecometric climatic indicators
167
of data and corresponding ecometric climatic indexes. This is also conditioned by
the fact that the countries of South-Eastern Europe where the Republic of Moldova
is also situated, as opposed to the countries of Western and Northern Europe, are
characterized by the lack of sufficient water resources, are at risk of becoming
countries with a an additional factor limiting economic development unless a strict
policy of rational water use is promoted.
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